Exploring Quantum Superpositions of Macroscopic Systems as Detectors for Particles
I delve into the promising possibilities of using quantum superposition in macroscopic systems as detectors for weakly interacting relativistic particles. I take a closer look at the specific example of neutrinos with MeV-scale energy scattering from a solid object via neutral-current neutrino-nucleus scattering. Using parameters from a nuclear fission reactor as an (anti-)neutrino source, I establish the optimal spatial separation between the quantum superposed components for maximum sensitivity in detecting these particles. In addition, I study the temporal evolution of the sensing system, taking into account the effects of cooling and background suppression. Through my research, I demonstrate that a single gram scale mass placed in a superposition of spatial components separated by 10^(-14) m can yield a potentially measurable relative phase between quantum superposed components, opening up exciting possibilities for future applications.
Furthermore, I investigate the broader implications of utilizing quantum superpositions in sensing. By analyzing the effects of scattering interactions between directional environments and systems in quantum superposition, I discovered that there exists an optimal superposition size for measuring incoming particles via a relative phase. An interesting feature of my research is the observation of a novel limiting behaviour in the properties of the system’s density matrix, which is linked to the wavelength of the scatterer. This highlights the anisotropy of the environment and its impact on quantum sensing.
As a platform for a practical realisation of macroscopic superpositions, I investigate an atom-nanoparticle system and discuss the possibility of treating the nanoparticle as a spatial qubit.
Overall, my thesis presents a comprehensive examination of the potential of quantum superposition in macroscopic systems as detectors for weakly interacting relativistic particles. It demonstrates that exploiting quantum mechanics for directional sensing offers unprecedented possibilities and has the potential to revolutionize the field of quantum sensing.
https://discovery.ucl.ac.uk/id/eprint/10178897/3/Thesis_Eva_Kilian.pdf